Age-hardening cu-p-ni alloy containing zr



Dec. 22, 1964 TOSHIO DOI AGE-HARDENING Cu-P-Ni ALLOY CONTAINING Zr Filed March 7, 1963 rnuEnToR HmoR HE y United States Patent 3,162,529 AGE-HARDENING Cn=P-Ni ALLOY CONTAWING Zr Toshio Del, Tokyo, Japan, assignor to Hitachi, Ltd, Tokyo, Japan, a corporation of Japan Filed Mar. 7, 1963, Ser. No. 263,668 Claims priority, application Japan Mar. 10, 1962 4 Claims. (Cl. 75153) The present invention relates to age-hardening copper alloys and is intended to provide those having fine crystal grains.

Copper-phosphorus-nickel alloys and other copper alloys such as copper-chromium, copper-beryllium and copper-titanium are known as age hardening alloys.

Among others, the copper-phosphorus-nickel alloys are in use as a grid material for ultrahigh-frequency receiver tubes, but have previously involved a difiiculty that their crystal grains grow coarse when heated to a temperature of 500 C. or higher.

To obviate the above difliculty met with previous copper-phosphorus-nickel alloys, the present invention provides a copper alloy containing, by weight, from 0.5% to 1.5% of nickel, from 0.1% to 0.3% of phosphorus, and from 0.05% to 0.3% of zirconium, the balance of the alloy being substantially copper and possibly including traces of silver, cobalt, chromium and beryllium.

The composition of copper-phosphorus-nickel alloy previously recommended to obtain a desirable age-hardening characteristic has included the sum of nickel and phosphorus contents of from 1.25% to 1.5%, the two elements being contained in the ratio of 5: 1.

The precipitation in such copper-phosphorus-nickel alloy remains substantially unchanged when added with zirconium of up to 0.3%, but no precipitation hardening occurs in such alloy when more than 0.3% of zirconium is contained. As regards the grain size, it is reduced by the addition of zirconium but only to a limited extent as long as the zirconium content does not exceed 0.05%. As the zirconium content exceeds 0.05 however, the reduction in grain size grows extreme because of the appearance of zirconium in the precipitated structure.

The following table lists various properties obtained with copper-phosphorus-nickel alloys having the same nickel and phosphorus contents of 1.1% and 0.22%, respectively, but having different zirconium contents in the range of zero to 1%. The heat treatment included a solution treatment at 800 Q. followed by water quenching and a one-hour aging at about 500 C. The values listed are average for five samples prepared for each alloy number.

S=aiter solution tretament; A=aiter aging.

It has also been found that a 75 cold working inserted between the solution treatment and aging more or less increases the specific resistance of the alloys, but is effective to increase their tensile strength to a substantial extent as listed below:

i Alloy No I 1 2 3 l 4 g 5 It will be readilly recognized from the above two tables that the tensile strength before aging increased to a slight extent by addition of zirconium but beyond that extent remains substantially unchanged even if the added amount of zirconium is increased. The tensile strength as obtained after aging also increased as zirconium was added, but after the Zr content had reached approximately 0.1% the tensile strength rather decreased. The aging had substantially no effect upon the tensile strength of those alloys which contain from 0.3% to 0.4% or more of zirconium. Substantially the same tendency was observed also with the specific resistance. It will be appreciated that alloys containing from 0.3% to 0.4% or more of zirconium are not susceptible to age-hardening. In case the cold Working is performed after the solution treatment, it has been observed that the zirconium content giving a maximum tensile strength is reduced. The alloys listed above had the following grain sizes when subjected to a solution treatment at 800 C. followed by water quenching, a cold working and a one-hour heating at 1000 C.

The accompanying drawing represents a logarithmic chart showing the relationship between the grain size and the zirconium content as obtained in the above and other experiments conducted with the copper-phosphorus-nickel alloy. As observed, the chart may be divided into two regions corresponding to the zirconium content of less than 0.05 and that of 0.05% or more. In the range of zirconium content of not less than 0.05%, it is evi dent that the addition of zirconium is very effective to reduce the size of crystal grains. On the other hand, the age-hardening property of the alloy is the highest for the Zr content of from 0.05 to 0.25% and is reduced substantially to zero if the Zr content exceeds 0.3%. Thus, it is recognized that the range of Zr content in which the alloy may be ellectively age-hardened while being reduced in grain size is from 0.05 to 0.3%.

The alloy of the present invention is highly valuable in various industrial applications. One advantage of the alloy of the present invention is that since the grain size does not grow even when the alloy is heated to elevated temperatures, it performs excellently in deep-drawing operation. Another advantage is that it is readily agehardened at a temperature of from 300 C. to 600 C. to exhibit excellent mechanical properties compared with previous kinds of copper-phosphorus-nickel alloy. Other advantages include improved electric and thermal conductivities and lower cost.

What is claimed is:

1. An age-hardening copper alloy consisting essentially,

by Weight, of from 0.5 to 1.5% of nickel, from 0.1%

about 5:1, and zirconium from 0.05% to not more than phosphorus and 0.05% to 0.3% of zirconium, the balance 7 consisting essentially of copper, the ratio of nickel to phosphorus being about '5 :1, all percentages being by weight.

References Cited in the file of this patent UNITED STATES PATENTS 2,137,282 Hensel et a1 Nov. 22, 1938 2,137,283 Hensel et' al Nov. 22, 1938 2,155,405 Ci'arnpton et. al Apr. 25, 1939 

1. AN AGE-HARDENING COPPER ALLOY CONSISTING ESSENTIALLY, BY WEIGHT, OF FROM 0.5% TO 1.5% OF NICKEL, FROM 0.1% TO 0.3% OF PHOSPHORUS, AND FROM 0.5 TO 0.3% ZIRCONIUM, THE BALANCE CONSISTING ESSENTIALLY OF COPPER AND INCLUDING TRACES OF SILVER, COBALT, CHROME AND BERYLLIUM. 